Multi-layer flexible optical circuit

Abstract

A multi-layer optical circuit includes a plurality of stacked flexible substrates and an adhesive between adjacent substrate layers. A plurality of optical fibers are positioned between adjacent substrate layers. The flexible substrates of adjacent substrate layers are secured together by the adhesive and directly engage the plurality of optical fibers between the adjacent substrate layers.

1 . A multi-layer optical circuit comprising:
 a plurality of stacked flexible substrates layers;   an adhesive between adjacent substrate layers; and   a plurality of optical fibers positioned between adjacent substrate layers, the optical fibers between adjacent substrate layers defining a first optical fiber group and a second optical fiber group, wherein the adjacent substrate layers are secured together by the adhesive and directly engage the plurality of optical fibers between the adjacent substrate layers,   
     
     
         2 . The multi-layer optical circuit of claim I, wherein the adjacent substrate layers are directly engaged. 
     
     
         3 . The multi-layer optical circuit of  claim 3 , wherein at least one of the optical fibers of the first optical fiber group crosses over a plurality of optical fibers of the second optical fiber group at a crossover location. 
     
     
         4 . The multi-layer optical circuit of  claim 1 , wherein the crossover locations between adjacent substrate layers are offset to reduce a height of the multi-layer optical circuit. 
     
     
         5 . The multi-layer optical circuit of  claim 1 , wherein each of the plurality of optical fibers has a length and the plurality of optical fibers over substantially their entire length directly engage the flexible substrates of their respective adjacent substrate layers. 
     
     
         6 . The multi-layer optical circuit of  claim 5 , wherein the plurality of optical fibers over their entire length other than at crossover locations directly engage the flexible substrates of their respective adjacent substrate layers. 
     
     
         7 . The multi-layer optical circuit of  claim 6 , wherein the crossover locations include at least one lower optical fiber and at least one upper optical fiber, and a lower substrate layer of adjacent substrate layers directly engages the at least one lower optical fiber at the crossover location and an upper substrate layer of adjacent substrate layers directly engages the at least one upper optical fiber at the crossover location. 
     
     
         8 . The multi-layer optical circuit of  claim 1 , wherein the plurality of optical fibers are secured between adjacent substrate layers without a conformal coating between the flexible substrates. 
     
     
         9 . The multi-layer optical circuit of  claim 1 , wherein the optical fibers have a diameter and the flexible substrates have a thickness, the thickness being less than 50% of the diameter. 
     
     
         10 . The multi-layer optical circuit of  claim 1 , wherein the optical fibers have a diameter and the flexible substrates have a thickness, the thickness being less than 30% of the diameter. 
     
     
         11 . The multi-layer optical circuit of  claim 1 , wherein each flexible substrate is approximately 0.025 mm thick. 
     
     
         12 . A multi-layer optical circuit comprising:
 a plurality of stacked flexible substrate layers;   an adhesive positioned between adjacent substrate layers; and   a plurality of optical fibers positioned between adjacent substrate layers and secured to at least one of the substrate layers by the adhesive, the optical fibers between adjacent substrate layers defining an optical fiber layer, wherein the flexible substrate layers of adjacent substrate layers directly engage each other except along the plurality of optical fibers.   
     
     
         13 . The multi-layer optical circuit of  claim 12 , wherein a first optical fiber of a first optical fiber layer crosses over a second optical fiber within the first optical fiber layer at a first crossover location. 
     
     
         14 . The multi-layer optical circuit of  claim 13 , wherein a first optical fiber of a second optical fiber layer crosses over a second optical fiber within the second optical fiber layer at a second crossover location, the first crossover location and the second crossover location being offset to reduce a height of the multi-layer optical circuit. 
     
     
         15 . The multi-layer optical circuit of  claim 12 , wherein each of the plurality of optical fibers has a length and the plurality of optical fibers over substantially their entire length directly engage the flexible substrate layers of their respective adjacent substrate layers. 
     
     
         16 . The multi-layer optical circuit of  claim 15 , wherein the plurality of optical fibers over their entire length other than at crossover locations directly engage the flexible substrate layers of their respective adjacent substrate layers. 
     
     
         17 . The multi-layer optical circuit of  claim 16 , herein the crossover locations include at least one lower optical fiber and at least one upper optical fiber, and a lower substrate layer of adjacent substrate layers directly engages the at least one lower optical fl at the crossover location and an upper substrate layer of adjacent substrate layers directly engages the at least one upper optical fiber at the crossover location. 
     
     
         18 . The multi-layer optical circuit of  claim 12  wherein the plurality of optical fibers are secured between adjacent substrate layers without a conformal coating between the flexible substrate layers. 
     
     
         19 . A method of fabricating a multi-layer optical circuit comprising:
 providing a first flexible substrate with an adhesive thereon;   routing a first plurality of optical fibers onto the first flexible substrate to form a first optical fiber layer;   providing a second flexible substrate;   providing an adhesive on one of the first and second flexible substrates;   directly engaging the first flexible substrate with the second flexible substrate to capture the first plurality of optical fibers between the first flexible substrate and the second flexible substrate;   routing a second plurality of optical fibers onto the second flexible substrate to form a second optical fiber layer;   providing a third flexible substrate; and   directly engaging the second flexible substrate with the third flexible substrate to capture the second plurality of optical fibers between the second flexible substrate and the third flexible substrate.   
     
     
         20 . The method of  claim 19 , further including securing the first flexible substrate to a work surface before routing the first plurality of optical fibers, the routing step includes laying a first optical fiber of the first optical fiber layer in an arcuate manner over a second optical fiber within the first optical fiber layer at a first crossover location to define a crossover curve, and releasing the first flexible substrate from the work surface and permitting the first optical fiber to straighten from the crossover curve.